1. Field
The present disclosure relates to cold-gas dynamic spray deposition, and more particularly to nozzles for cold-gas dynamic spray deposition systems.
2. Description of Related Art
Cold-gas dynamic-spray processes, commonly referred to as ‘cold spray’, are deposition processes in which a jet of compressed carrier gas accelerates fine, solid powder materials toward a workpiece. The solid particles are typically metals, but can include polymers, ceramics, or metal composites. As the solid particles impact the workpiece surface the particles bond to the surface of the workpiece and form a deposition integral with the underlying workpiece. The prevailing theory for the mechanism by which the solid particles deform and bond during cold spray is that, during impact, the solid particles undergo plastic deformation. The deformation disrupts the thin, oxide surfaces and films of the solid particles and/or workpiece surface to achieve conformal contact between the solid particles and workpiece surface. Conformal contact of the solid particles in conjunction with the impact contact pressure impact promotes solid-state bonding of the solid particles and workpiece surface.
Cold spray nozzles typically accelerate solid particulate by directing a conveying motive gas entraining the solid particulate through a flow-restricting orifice. The gas undergoes a temperature reduction and pressure reduction while increasing velocity at it traverses the nozzle. This accelerates the entrained particulate to velocities sufficient to induce plastic deformation.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved cold spray nozzles. The present disclosure provides a solution for this need.